United Nations (CNN) -- The United Nations Security Council voted Wednesday to impose new sanctions on Iran to try to force it to suspend its nuclear program.

U.S. President Barack Obama called them "the toughest sanctions ever faced by Iran."

But Iranian President Mahmoud Ahmadinejad said they were like a "used handkerchief that should be dumped in a garbage can," Iranian media reported.

"They cannot harm the Iranian nation," he said, according to the semi-official Iranian Students News Agency.

The vote was 12-2, with Lebanon abstaining. Brazil and Turkey opposed the sanctions -- the fourth set of measures to try to rein in Iran since 2006.

"True security will not come through nuclear weapons," Obama said. He called Iran the only signer of the nuclear Non-Proliferation Treaty "that cannot convince the IAEA that its nuclear program is intended for peaceful purposes," referring to the U.N.'s International Atomic Energy Agency.

"What is at stake today is the credibility of the Security Council, which has turned into the tool in the toolbox of a few countries that do not hesitate to abuse it," Mohammad Khazaee said.

He reiterated Iran's long-standing insistence that the country is not seeking nuclear weapons, pointing out that its Supreme Leader, Ayatollah Ali Khamenei, has declared them "religiously forbidden."

But Obama -- speaking in Washington at the same time Khazaee was speaking at the United Nations in New York -- said Iran had failed to live up to its responsibilities.

He said Iran had concealed a nuclear enrichment program near the city of Qom and "violated obligations to suspend uranium enrichment."

The U.S. ambassador to the United Nations, Susan Rice, dismissed Khazaee's comments as "ridiculous rhetoric."

"These sanctions are not directed at the Iranian people," Rice said earlier, immediately after the vote.

Instead, they "aim squarely at the nuclear ambitions" of the regime, she said, calling them "as tough as they are smart and precise."

She placed the blame for the sanctions squarely on Iran.

"We are at this point because the government of Iran has chosen clearly and willfully to violate its commitments to the IAEA and the resolutions of this council," she said.

Israel, which fears any Iranian nuclear weapons would be directed at it, welcomed the vote but said the sanctions resolution alone is not enough.

"A broad and adamant international action that will pinpoint to the Iranian regime the price that goes along with violating the International requirements is needed in order to make clear to Iran the demands of the international community," Israel's Foreign Ministry said in a statement.

"The implications of the connection between Iran's extremist ideology and nuclear weapons will be catastrophic," it warned.

Iran warned before the vote that it would break off negotiations with the United States and its allies if new sanctions were put in place.

"These hasty measures are mere deviation from the path of constructive transaction and an indicative of the fact that the other parties rather prefer confrontation," Khazaee said Tuesday.

"In such a condition, the Islamic Republic of Iran has no choice but to react accordingly in the way it considers appropriate," he said.

But the international community is prepared to keep negotiating, the British ambassador to the United Nations said.

"We are prepared to continue dialogue and interaction with Iran," Sir Mark Lyall Grant said on behalf of his country, China, France, Germany, Russia and the United States -- the countries negotiating with Tehran over its nuclear program.

They "reaffirm our determination and commitment to seek an early negotiated solution to the Iranian nuclear issue," he said.

The foreign ministers of the six nations issued a statement saying the resolution "keeps the door open for continued engagement" with Iran. It concluded by saying, "We expect Iran to demonstrate a pragmatic attitude and to respond positively to our openness towards dialogue and negotiations."

The United States and its allies fear that Iran is trying to develop nuclear weapons. Tehran denies it, saying its nuclear program is for energy and medical use.

The new sanctions include cargo inspections, new controls on Iranian banks "to block the use of the international financial system ... to fund and facilitate nuclear proliferation," restrictions on the Islamic Revolutionary Guard Corps, a new U.N. panel of experts to help monitor and enforce sanctions, and asset freezes on 40 entities and an individual, Rice said.

The individual is Javad Rahiqi, the head of Iran's Atomic Energy Organization, who will also be subject to a travel ban.

The sanctions do not include restrictions on gas imports to Iran, a possibility the United States had floated but which China and Russia opposed.

Khazaee listened impassively as Rice spoke, the hint of a smile playing on his face.

Turkey and Brazil recently struck a deal with Iran, under which Turkey would act as an intermediary for Iran to get highly enriched uranium from abroad.

That deal was "automatically wiped out" by the passage of the sanctions resolution, Ahmadinejad spokesman Ali Akbar Javanfekr told CNN.

Washington and its allies want Iran to stop enriching uranium itself. Iran says it has been enriching it to the level where it can sustain a nuclear reaction.